CN115692789B - Cold start control method for fuel cell stack - Google Patents

Abstract

The invention provides a cold start control method of a fuel cell stack, which comprises the following steps: acquiring initial temperature and initial impedance of a galvanic pile, inquiring a cold start control curve graph according to the initial temperature and the initial impedance to obtain a fuel metering ratio and an oxidant metering ratio, and introducing fuel and oxidant into the galvanic pile based on the fuel metering ratio and the oxidant metering ratio; and loading current to the electric pile, and if the temperature of the electric pile is greater than or equal to the preset temperature, successfully starting cold. The cold start control method can shorten the loading time of cold start of the electric pile, and does not need external auxiliary heating.

Description

A cold start control method for a fuel cell stack

technical field

The invention belongs to the technical field of fuel cells, and relates to a cold start control method of a fuel cell stack.

Background technique

The cold start control of the fuel cell stack is an important link in the fuel cell control strategy, and the cold start performance of the fuel cell stack is a key indicator of the applicability of the fuel cell in low temperature environments. At present, the start-up problem of proton exchange membrane fuel cells has not been completely solved, especially for the low-temperature unassisted self-starting method and control strategy of fuel cell stacks without systematic elaboration. There are no clear parameters for the self-starting conditions and control strategies of fuel cell stacks. The reasons are: on the one hand, it is difficult to control the water balance of proton exchange membranes at low temperatures. When the water in the membranes is too low, the efficiency of mass transfer is low. When there is too much water, it is easy to freeze and block the fuel reaction channel; on the other hand, during the cold start process of the stack, there will be local lack of air and water blockage, and the consistency of the stack is poor, which affects the life of the stack and the overall performance.

At present, the existing cold start methods mostly adopt the form of auxiliary heating or the way of controlling the external circuit. CN103825037A discloses a fuel cell cold start rapid heating system, which includes a hydrogen delivery pipeline and a fuel cell stack, and the hydrogen delivery pipeline transports the hydrogen The flow channel to the anode side of the fuel cell stack also includes a heater, a thermometer and a battery control system; the heater is arranged on the hydrogen delivery pipeline to heat the hydrogen; the thermometer is arranged on the fuel cell stack Internally, it is used to measure the temperature of the electric stack; the data acquisition end of the battery control system is connected to the thermometer, and the output end is connected to the heater, and the opening of the heater is controlled according to the temperature inside the electric stack measured by the thermometer with off. CN113707904A discloses a self-heating fuel cell vehicle cold start heater and heating method. The heater includes a self-heating agent tank body, the inner cavity of the self-heating agent tank body is filled with self-heating agent powder, and the self-heating agent tank body is provided with an air inlet connected with an air compressor, and the self-heating agent powder is connected to the air inlet The redox reaction of the incoming air generates a large amount of heat, so that the parts that need to be heated can be heated rapidly during the cold start process. The above-mentioned patents use auxiliary heating to achieve cold start, and need to add heaters and other components, which increases the complexity and cost of the system.

Other methods without external auxiliary heating include: adopting the loading form of multiple current density gradients or adopting the method of intermittently stopping the supply of the oxidant or heating by the reaction of hydrogen and oxygen on the same side. CN114188570A discloses a cold start method, device and vehicle of a fuel cell stack. The method includes: after the shutdown and purging are completed, hydrogen gas is fed into the anode inlet of the stack based on a first preset parameter, and hydrogen is fed to the stack cathode. Oxygen is introduced into the inlet. If it is detected that the minimum voltage and the average voltage of the batteries in the stack meet the first preset condition, then the first current is applied to the stack step by step according to the preset current density gradient. If the detected minimum voltage and average voltage meet the second preset condition, hydrogen gas is fed to the anode inlet of the stack based on the second preset parameter, and oxygen is fed to the cathode inlet of the stack, and the target current density is loaded to the stack value of the second current. If the detected minimum voltage and the average voltage meet the third preset condition, and the detected temperature of the stack coolant outlet is within a preset temperature range, then the cold start of the stack is completed. However, the above-mentioned multi-current density gradient loading method increases the repeatability of the control strategy, and the start-up time is long. In addition, the method of heating with hydrogen and oxygen on the same side can easily cause permanent damage to the fuel cell stack. At the same time, the above cold start method cannot adaptively adjust the metering ratio of fuel and oxidant according to the actual cold start state, resulting in waste of fuel and oxidant, further reducing the efficiency of the fuel cell stack system.

In addition, the existing method requires a small range of water content in the fuel cell stack during low-temperature cold start, which cannot meet the actual cold start state of the fuel cell stack, which is likely to cause cold start failure and lack of protection for the fuel cell stack.

Therefore, there is an urgent need for a simple fuel cell stack cold start method that does not require external auxiliary heating.

Contents of the invention

Aiming at the deficiencies in the prior art, the object of the present invention is to provide a cold start control method for fuel cell stacks, which reduces redundant control procedures, is easy to implement, and does not require external auxiliary heating, thereby simplifying the system structure , reduce system cost.

For reaching this purpose, the present invention adopts following technical scheme:

In a first aspect, the present invention provides a cold start control method of a fuel cell stack, the cold start control method comprising:

(1) Obtain the initial temperature and initial impedance of the stack, query the cold start control curve according to the initial temperature and the initial impedance, obtain the fuel metering ratio and the oxidant metering ratio, based on the fuel metering ratio and the oxidant metering Feed fuel and oxidant into the electric stack;

(II) Load current to the stack. If the stack temperature is greater than or equal to the preset temperature, the cold start is successful.

The invention provides a cold start control method of a fuel cell stack, the cold start control method reduces redundant control programs, shortens the loading time of the cold start of the stack, and the method does not require external auxiliary heating, thereby enabling Simplify the structure of the system and reduce the cost of the system. In addition, the present invention determines the optimal fuel metering ratio and the optimal oxidant metering ratio according to the cold start control curve, which can effectively improve the fuel and oxidant use efficiency and cold start success rate, and widen the range of water content in the stack during cold start , thereby improving the applicability of the fuel cell stack in winter and cold regions.

It should be noted that the cold start control curve diagram (MAP diagram) of the present invention is a relationship diagram between the temperature of the fuel cell stack, the high frequency impedance and the raw material metering ratio, and the cold start control curve diagram includes temperature, high frequency Impedance versus fuel metering ratio graph, and temperature, high frequency impedance versus oxidant metering ratio graph.

The optimal fuel metering ratio and the best oxidizer metering ratio determined according to the cold start control curve diagram are the minimum fuel metering ratio and the minimum oxidizer metering ratio required for the cold start of the stack, and the fuel and oxidizer metering ratios are increased on this basis, It can improve the success rate of cold start, but considering factors such as raw material costs, the increased metering ratio is limited.

In the present invention, a series of tests are designed to obtain the cold start control curve. Exemplarily, the method for obtaining the cold start control curve of the fuel metering ratio is as follows: the oxidant metering ratio and the cold start temperature are kept constant, and the water content of the stack is changed. To change the initial impedance of the stack, and then collect the minimum fuel metering ratio required for the successful cold start of the stack under different initial impedances, obtain a curve at a certain temperature after the data is summarized, and then change the cold start temperature for multiple tests, then you can A cold start control graph is obtained with respect to fuel stoichiometry. The cold start control curve diagram about the stoichiometric ratio of the oxidant can be obtained in the same way.

As a preferred technical solution of the present invention, the cold start control method specifically includes the following steps:

Step 1: Set the average single-chip voltage protection value U ₀ , the minimum single-chip voltage protection value U ₁ and the first current density C ₀ for the cold start of the fuel cell stack, and proceed to step 2;

Step 2: Obtain the initial temperature T ₀ and initial impedance H ₀ of the stack, query the cold start control curve according to the initial temperature T ₀ and initial impedance H ₀ , and obtain the fuel metering ratio F ₀ and oxidant metering ratio O ₀ , based on fuel metering Ratio F ₀ and oxidant metering ratio O ₀ feed fuel and oxidant to the stack;

Step 3: Set the rate V ₀ of the stack loading current and load the current, obtain the loading current density, and enter step 4 for logical judgment;

Step 4: Judging whether the obtained current density is greater than or equal to the first current density C ₀ , if the judgment result is yes, go to step 9;

Step 9: Set the fuel metering ratio F ₁ and the oxidant metering ratio O ₁ , and feed the fuel and the oxidant into the stack based on the fuel metering ratio F ₁ and the oxidant metering ratio O ₁ , and proceed to step 10;

Step 10: load current to the stack to the second current density C ₁ , and proceed to step 11;

Step 11: Obtain the stack temperature, and proceed to step 12 for logical judgment;

Step 12: Judging whether the stack temperature is greater than or equal to the preset temperature, if the judgment result is yes, the cold start of the stack is successful.

In the present invention, the initial impedance H ₀ is the initial high-frequency impedance of the stack.

As a preferred technical solution of the present invention, said step 4: if the judgment result is no, enter step 5 for logical judgment;

Step 5: Judging whether the average single-chip voltage is greater than the average single-chip voltage protection value U ₀ and the lowest single-chip voltage is greater than the lowest single-chip voltage protection value U ₁ during the loading process. If the judgment result is yes, return to step 3. If it is judged If the result is no, go to step 6;

Step 6: Run stably at the current density described in step 3, and record the stabilization time S ₁ , and proceed to step 7 for logical judgment;

Step 7: Judging whether the stabilization time S ₁ is less than the protection time S ₀ , if the judgment result is yes, proceed to step 5 for logical judgment, if the judgment result is no, proceed to step 8;

Step 8: Set fuel metering ratio increment ΔF and oxidant metering ratio increment ΔO, and feed fuel and oxidant to the stack based on the increased fuel metering ratio and oxidant metering ratio, and proceed to step 5 for logical judgment.

In the present invention, step 5 also includes the step of acquiring the average single-chip voltage and the lowest single-chip voltage of the stack; after the acquisition, logical judgment is performed.

The present invention sets the voltage protection strategy. By increasing the fuel/oxidant metering ratio in step 8, the phenomenon of cold start failure caused by too low single-chip voltage or low overall average voltage during the cold start process is eliminated, and the cold start of the stack is improved. The voltage consistency during start-up protects the performance of the fuel cell stack and improves the service life.

In the present invention, steps 3-8 can be repeated continuously until the target current density C ₀ is loaded.

As a preferred technical solution of the present invention, the step 12: if the judgment result is no, go to step 13;

Step 13: Run stably at the second current density _C1 for a preset time, and then go to Step 11.

As a preferred technical solution of the present invention, the average single-chip voltage protection value _U0 is 0.2-0.5V, for example, it can be 0.2V, 0.25V, 0.3V, 0.35V, 0.4V, 0.45V or 0.5V, etc. .

Preferably, the minimum single-chip voltage protection value U ₁ is -0.2˜0.1V, for example, it may be -0.2V, -0.15V, -0.1V, -0.05V, 0V, 0.05V or 0.1V.

Preferably, the first current density C ₀ is 0.4-0.65A/cm ² , for example, 0.4A/cm ² , 0.42A/cm ² , 0.45A/cm ² , 0.47A/cm ² , 0.5A/cm 2 cm ² , 0.52A/cm ² , 0.55A/cm ² , 0.57A/cm ² , 0.6A/cm ² , 0.62A/cm ² or 0.65A/cm ² etc.

Preferably, the initial temperature T ₀ is -30 to -5°C, for example, it may be -30°C, -25°C, -20°C, -15°C, -10°C or -5°C.

As a preferred technical solution of the present invention, based on the fuel metering ratio F ₀ , the pressure of the fuel fed is 70-100 kPag, such as 70 kPag, 75 kPag, 80 kPag, 85 kPag, 90 kPag, 95 kPag or 100 kPag.

Preferably, based on the oxidant stoichiometric ratio O ₀ , the pressure of feeding the oxidant is 60-90 kPag, such as 60 kPag, 65 kPag, 70 kPag, 75 kPag, 80 kPag, 85 kPag or 90 kPag.

As a preferred technical solution of the present invention, the rate _V0 of the loading current in the step 3 is 10-20A/s, for example, it can be 10A/s, 11A/s, 12A/s, 13A/s, 14A/s , 15A/s, 16A/s, 17A/s, 18A/s, 19A/s or 20A/s, etc.

Preferably, the protection time S ₀ is 5-30s, for example, it may be 5s, 7s, 10s, 12s, 15s, 17s, 20s, 22s, 25s, 27s or 30s.

In the present invention, the protection time is the minimum single-chip protection time.

Preferably, the fuel metering ratio increment ΔF is 0.1˜0.3, such as 0.1, 0.12, 0.15, 0.17, 0.2, 0.22, 0.25, 0.27 or 0.3.

Preferably, the oxidant metering ratio increment ΔO is 0.2-0.5, such as 0.2, 0.22, 0.25, 0.27, 0.3, 0.32, 0.35, 0.37, 0.4, 0.42, 0.45, 0.47 or 0.5.

In the present invention, compared to the fuel metering ratio F ₀ , the increment of the fuel metering ratio F ₁ is 0.1 to 0.3 to increase the consumption of fuel; compared to the oxidant metering ratio O ₀ , the increment of the oxidant metering ratio O ₁ is 0.2 to 0.5 to increase the amount of oxidant.

As a preferred technical solution of the present invention, the fuel metering ratio _F1 is 1.2 to 1.8, such as 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1. or 1.8 etc.

Preferably, the oxidant stoichiometric ratio O ₁ is 2.0˜2.5, for example, it may be 2.0, 2.05, 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.45 or 2.5.

Preferably, based on the fuel metering ratio F ₁ , the pressure of the injected fuel is 100-140 kPag, such as 100 kPag, 105 kPag, 110 kPag, 115 kPag, 120 kPag, 125 kPag, 130 kPag, 135 kPag or 140 kPag.

Preferably, based on the oxidant metering ratio O ₁ , the pressure of feeding the oxidant is 80-120 kPag, such as 80 kPag, 85 kPag, 90 kPag, 95 kPag, 100 kPag, 105 kPag, 110 kPag, 115 kPag or 120 kPag.

As a preferred technical solution of the present invention, the second current density C ₁ is 0.6-0.8A/cm ² , such as 0.6A/cm ² , 0.62A/cm ² , 0.65A/cm ² , 0.67A /cm ² , 0.7A/cm ² , 0.72A/cm ² , 0.75A/cm ² , 0.78A/cm ² , 0.8A/cm ^{2 ,} etc.

Preferably, the rate of loading current in step 10 is 10-20A/s, which can be 10A/s, 11A/s, 12A/s, 13A/s, 14A/s, 15A/s, 16A/s, 17A /s, 18A/s, 19A/s or 20A/s etc.

As a preferred technical solution of the present invention, the preset temperature is 50-60°C, such as 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C , 59°C or 60°C, etc.

But not limited to the listed values, other unlisted values within the range of values are also applicable.

The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above-mentioned numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the ranges. The specific pip value to include.

Compared with prior art, the beneficial effect of the present invention is:

The invention provides a cold start control method of a fuel cell stack, the cold start control method reduces redundant control programs, shortens the loading time of the cold start of the stack, and the method does not require external auxiliary heating, thereby enabling Simplify the structure of the system and reduce the cost of the system. In addition, the present invention determines the optimal fuel metering ratio and the optimal oxidant metering ratio according to the cold start control curve, which can effectively improve the fuel and oxidant use efficiency and cold start success rate, and widen the range of water content in the stack during cold start , thereby improving the applicability of the fuel cell stack in winter and cold regions.

Description of drawings

Fig. 1 is a control flow chart of a fuel cell stack cold start provided by a specific embodiment of the present invention.

Fig. 2 is a cold start control curve diagram regarding fuel provided by an embodiment of the present invention.

Fig. 3 is a graph of the cold start control curve of the oxidant provided by the embodiment of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

In a specific embodiment, the present invention provides a cold start control method of a fuel cell stack, and the cold start control method specifically includes the following steps (as shown in FIG. 1 ):

Step 1: Set the average single-chip voltage protection value U ₀ (0.2-0.5V), the minimum single-chip voltage protection value U ₁ (-0.2-0.1V) and the first current density C ₀ ( 0.4～0.65A/cm ² ), go to step 2;

Step 2: Obtain the initial temperature T ₀ (-30～-5°C) and initial impedance H ₀ of the stack, query the cold start control curve (MAP graph) according to the initial temperature T ₀ and initial impedance H ₀ , and obtain the fuel metering ratio F ₀ and oxidant metering ratio O ₀ , based on fuel metering ratio F ₀ and oxidant metering ratio O ₀ , feed fuel (pressure 70-100kPag) and oxidant (pressure 60-90kPag) to the stack;

Step 3: Set the stack loading current rate V ₀ (10-20A/s) and load the current, obtain the loading current density, and proceed to step 4 for logical judgment;

Step 4: Judging whether the obtained current density is greater than or equal to the first current density C ₀ , if the judgment result is yes, proceed to step 9; if the judgment result is no, proceed to step 5 for logical judgment;

Step 5: Obtain the average single-chip voltage and the lowest single-chip voltage of the stack, and determine whether the average single-chip voltage is greater than the average single-chip voltage protection value U ₀ during the loading process, and the lowest single-chip voltage is greater than the lowest single-chip voltage protection value U _1. If the judgment result is yes, return to step 3; if the judgment result is no, go to step 6;

Step 6: Run stably at the current density described in step 3, and record the stabilization time S ₁ , and proceed to step 7 for logical judgment;

Step 7: Judging whether the stabilization time S ₁ is less than the protection time S ₀ (5-30s), if the judgment result is yes, proceed to step 5 for logical judgment, if the judgment result is no, proceed to step 8;

Step 8: Set fuel metering ratio increment ΔF (0.1-0.3) and oxidant metering ratio increment ΔO (0.2-0.5), and feed fuel and oxidant to the stack based on the increased fuel metering ratio and oxidant metering ratio , go to step 5 to make a logical judgment;

Step 9: Set fuel metering ratio F ₁ (1.2-1.8) and oxidant metering ratio O ₁ (2.0-2.5), and feed fuel and oxidant into the stack based on fuel metering ratio F ₁ and oxidant metering ratio O ₁ , enter Step 10;

Step 10: load current to the stack to the second current density C ₁ (0.6-0.8A/cm ² ), the rate of current loading is 10-20A/s, go to step 11;

Step 11: Obtain the stack temperature, and proceed to step 12 for logical judgment;

Step 12: Determine whether the stack temperature is greater than or equal to the preset temperature (50-60°C), if the judgment result is yes, then the cold start of the stack is successful; if the judgment result is no, go to step 13;

Step 13: Run stably at the second current density _C1 for a preset time, and then go to Step 11.

Example 1

This embodiment provides a cold start control method for a fuel cell stack, which specifically includes the following steps:

Step 1: Set the average single-chip voltage protection value U ₀ (0.4V), the minimum single-chip voltage protection value U ₁ (0.2V) and the first current density C ₀ (0.6A/cm ² ), go to step 2;

Step 2: Obtain the initial temperature T ₀ (-20°C) and initial impedance H ₀ of the stack, and query Figure 2 according to the initial temperature T ₀ and initial impedance H ₀ to obtain the fuel metering ratio F ₀ , and query Figure 3 to obtain the oxidant metering ratio O ₀ , based on the fuel metering ratio F ₀ and the oxidant metering ratio O ₀ , the fuel (pressure is 90kPag) and oxidant (pressure is 70kPag) are passed into the stack;

Step 3: Set the rate V ₀ (20A/s) of the stack loading current and load the current, obtain the loading current density, and enter step 4 for logical judgment;

Step 4: Judging whether the obtained current density is greater than or equal to the first current density C ₀ , if the judgment result is yes, go to step 9;

Step 9: Set the fuel metering ratio F ₁ (1.5) and the oxidant metering ratio O ₁ (2.1), and feed the fuel and the oxidant into the stack based on the fuel metering ratio F ₁ and the oxidant metering ratio O ₁ , and enter step 10;

Step 10: load current to the stack to the second current density C ₁ (0.8A/cm ² ), the rate of current loading is 20A/s, and go to step 11;

Step 11: Obtain the stack temperature, and proceed to step 12 for logical judgment;

Step 12: Judging whether the stack temperature is greater than or equal to the preset temperature (50°C), if the judgment result is yes, the stack cold start is successful; if the judgment result is no, go to step 13; if the first judgment result is no, go to step 13 ;

Step 13: Run stably at the second current density _C1 for a preset time (60s), enter step 11, obtain the temperature, and then judge in step 12. If the judgment result is yes, the stack cold start is successful.

Example 2

This embodiment provides a cold start control method for a fuel cell stack, which specifically includes the following steps:

Step 1: Set the average single-chip voltage protection value U ₀ (0.2V), the minimum single-chip voltage protection value U ₁ (-0.1V) and the first current density C ₀ (0.5A/cm ² ), go to step 2;

Step 2: Obtain the initial temperature T ₀ (-30°C) and initial impedance H ₀ of the stack, and query Figure 2 according to the initial temperature T ₀ and initial impedance H ₀ to obtain the fuel metering ratio F ₀ , and query Figure 3 to obtain the oxidant metering ratio O ₀ , feed fuel (pressure is 100kPag) and oxidant (pressure is 80kPag) to the stack based on fuel metering ratio F ₀ and oxidant metering ratio O ₀ ;

Step 3: Set the stack loading current rate V ₀ (10A/s) and load the current, obtain the loading current density, and proceed to step 4 for logical judgment;

Step 4: Judging whether the obtained current density is greater than or equal to the first current density C ₀ , if the judgment result is yes, go to step 9; if the judgment result is no, go to step 5 for logical judgment; if the first judgment result is no, go to step 5 ;

Step 5: Obtain the average single-chip voltage and the lowest single-chip voltage of the stack, and determine whether the average single-chip voltage is greater than the average single-chip voltage protection value U ₀ during the loading process, and the lowest single-chip voltage is greater than the lowest single-chip voltage protection value U _1. If the judgment result is yes, return to step 3; if the judgment result is no, go to step 6;

Step 6: Run stably at the current density described in step 3, and record the stabilization time S ₁ , and proceed to step 7 for logical judgment;

Step 7: Judging whether the stabilization time S ₁ is less than the protection time S ₀ (15s), if the judgment result is yes, proceed to step 5 for logical judgment, if the judgment result is no, proceed to step 8;

Step 8: Set fuel metering ratio increment ΔF(0.2) and oxidant metering ratio increment ΔO(0.3), and feed fuel and oxidant to the stack based on the increased fuel metering ratio and oxidant metering ratio, and enter step 5 make logical judgments;

Step 9: Set the fuel metering ratio F ₁ (1.6) and the oxidant metering ratio O ₁ (2.2), and feed the fuel and the oxidant into the stack based on the fuel metering ratio F ₁ and the oxidant metering ratio O ₁ , and enter step 10;

Step 10: Loading current to the stack to the second current density C ₁ (0.7A/cm ² ), the rate of loading current is 10A/s, and proceeding to step 11;

Step 11: Obtain the stack temperature, and proceed to step 12 for logical judgment;

Step 12: Judging whether the stack temperature is greater than or equal to the preset temperature (50°C), if the judgment result is yes, the stack cold start is successful; if the judgment result is no, go to step 13; if the first judgment result is no, go to step 13 ;

Step 13: Run stably for the preset time (80s) at the second current density _C1 , enter step 11, obtain the temperature and judge in step 12, if the judgment result is yes, the stack cold start is successful.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and those skilled in the art should understand that any person skilled in the art should be aware of any disclosure in the present invention Within the technical scope, easily conceivable changes or substitutions all fall within the scope of protection and disclosure of the present invention.

Claims (20)

1. A cold start control method of a fuel cell stack, characterized in that, the cold start control method specifically comprises the steps: Step 1: Set the average single-chip voltage protection value U ₀ , the minimum single-chip voltage protection value U ₁ and the first current density C ₀ for the cold start of the fuel cell stack, and proceed to step 2; Step 2: Obtain the initial temperature T ₀ and initial impedance H ₀ of the stack, query the cold start control curve according to the initial temperature T ₀ and initial impedance H ₀ , and obtain the fuel metering ratio F ₀ and oxidant metering ratio O ₀ , based on fuel metering Ratio F ₀ and oxidant metering ratio O ₀ feed fuel and oxidant to the stack; Step 3: Set the rate V ₀ of the stack loading current and load the current, obtain the loading current density, and enter step 4 for logical judgment; Step 4: Judging whether the obtained current density is greater than or equal to the first current density C ₀ , if the judgment result is yes, go to step 9; Step 9: Set the fuel metering ratio F ₁ and the oxidant metering ratio O ₁ , and feed the fuel and the oxidant into the stack based on the fuel metering ratio F ₁ and the oxidant metering ratio O ₁ , and proceed to step 10; Step 10: load current to the stack to the second current density C ₁ , and proceed to step 11; Step 11: Obtain the stack temperature, and proceed to step 12 for logical judgment; Step 12: Judging whether the stack temperature is greater than or equal to the preset temperature, if the judgment result is yes, the cold start of the stack is successful. 2. The cold start control method according to claim 1, characterized in that, said step 4: if the judgment result is no, enter step 5 for logical judgment; Step 5: Judging whether the average single-chip voltage is greater than the average single-chip voltage protection value U ₀ and the lowest single-chip voltage is greater than the lowest single-chip voltage protection value U ₁ during the loading process. If the judgment result is yes, return to step 3. If it is judged If the result is no, go to step 6; Step 6: Run stably at the current density described in step 3, and record the stabilization time S ₁ , and proceed to step 7 for logical judgment; Step 7: Judging whether the stabilization time S ₁ is less than the protection time S ₀ , if the judgment result is yes, proceed to step 5 for logical judgment, if the judgment result is no, proceed to step 8; Step 8: Set the fuel metering ratio increment ∆F and the oxidizer metering ratio increment ∆O, and feed fuel and oxidizer into the stack based on the increased fuel metering ratio and oxidant metering ratio, and proceed to step 5 for logical judgment. 3. The cold start control method according to claim 1, characterized in that, the step 12: if the judgment result is no, enter step 13; Step 13: Run stably at the second current density _C1 for a preset time, and then go to Step 11. 4. The cold start control method according to claim 1, wherein the average single chip voltage protection value _U0 is 0.2-0.5V. 5. The cold start control method according to claim 1, wherein the minimum single chip voltage protection value _U1 is -0.2~0.1V. 6. The cold start control method according to claim 1, wherein the first current density _C0 is 0.4-0.65A/cm². 7. The cold start control method according to claim 1, wherein the initial temperature T ₀ is -30~-5°C. 8 . The cold start control method according to claim 1 , characterized in that, based on the fuel metering ratio F ₀ , the pressure of the injected fuel is 70-100 kPag. 9 . The cold start control method according to claim 1 , characterized in that, based on the oxidant metering ratio O ₀ , the pressure of the oxidant is 60-90 kPag. 10. The cold start control method according to claim 1, characterized in that, the rate V ₀ of loading current in the step 3 is 10-20A/s. 11. The cold start control method according to claim 2, wherein the protection time _S0 is 5-30s. 12. The cold start control method according to claim 2, wherein the fuel metering ratio increment ΔF is 0.1-0.3. 13. The cold start control method according to claim 2, wherein the oxidant metering ratio increment ∆O is 0.2-0.5. 14. The cold start control method according to claim 1, characterized in that the fuel metering ratio _F1 is 1.2-1.8. 15. The cold start control method according to claim 1, wherein the stoichiometric ratio _O of the oxidant is 2.0-2.5. 16. The cold start control method according to claim 1, characterized in that, based on the fuel metering ratio F ₁ , the pressure of the injected fuel is 100-140 kPag. 17 . The cold start control method according to claim 1 , characterized in that, based on the oxidant metering ratio O ₁ , the pressure of the oxidant is 80-120 kPag. 18. The cold start control method according to claim 1, wherein the second current density _C1 is 0.6-0.8A/cm². 19. The cold start control method according to claim 1, characterized in that, the rate of applying current in the step 10 is 10-20A/s. 20. The cold start control method according to claim 1, wherein the preset temperature is 50-60°C.

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